std::unordered_map::operator[]

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C++ Standard Library
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Containers library
array (C++0x feature) vector deque forward_list (C++0x feature) list set multiset map multimap unordered_set (C++0x feature) unordered_multiset (C++0x feature) unordered_map (C++0x feature) unordered_multimap (C++0x feature) stack queue priority_queue
std::unordered_map
Member functions unordered_map::unordered_map unordered_map::~unordered_map unordered_map::operator= unordered_map::get_allocator Iterators unordered_map::begin unordered_map::cbegin unordered_map::end unordered_map::cend Capacity unordered_map::erase unordered_map::size unordered_map::max_size Modifiers unordered_map::clear unordered_map::insert unordered_map::emplace unordered_map::emplace_hint unordered_map::erase unordered_map::swap Lookup unordered_map::count unordered_map::find unordered_map::equal_range Bucket interface unordered_map::begin(int) unordered_map::end(int) unordered_map::bucket_count unordered_map::max_bucket_count unordered_map::bucket_size unordered_map::bucket Hash policy unordered_map::load_factor unordered_map::max_load_factor unordered_map::rehash unordered_map::reserve Observers unordered_map::hash_function unordered_map::key_eq

​T& operator[]( const Key& key );​	(1)	(C++0x feature)
​T& operator[]( Key&& key );​	(2)	(C++0x feature)

Inserts a new element to the container using key as the key and default constructed mapped value and returns a reference to the newly constructed mapped value. If an element with key key already exists, no insertion is performed and a reference to its mapped value is returned.

1) Essentially performs ​(insert(std::make_pair(key, T())).first)->second​.

2) Essentially performs ​(insert(std::make_pair(std::move(key), T())).first)->second​.

Contents 1 Parameters 2 Return value 3 Complexity 4 See also

Parameters

key

-

the key of the element to find

Return value

reference to the mapped value of the new element if no element with key key existed. Otherwise a reference to the mapped value of the existing element is returned.

Complexity

This section is incomplete

See also

at	access specified element with bounds checking (public member function)